<!DOCTYPE html>
<html lang="zh">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      function maximum(num1, num2, num3) {
        if (num1 > num2) {
          if (num1 > num3) {
            alert(num1)
          } else {
            alert(num3)
          }
        } else if (num2 > num3) {
          alert(num2)
        } else {
          alert(num3)
        }
      }
      maximum(
        Number(prompt("请输入第一个数：")),
        Number(prompt("请输入第二个数：")),
        Number(prompt("请输入第三个数："))
      )
    </script>
  </body>
</html>
